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-%% $Id: xy2cell.doc,v 3.3 1996/12/18 14:21:23 ross Exp $
-%%
-%% Xy-pic ``2-cell'' feature.
-%% Copyright (c) 1993-1996 Ross Moore <ross@mpce.mq.edu.au>
-%%
-%% This file is part of the Xy-pic package for graphs and diagrams in TeX.
-%% See the companion README and INSTALL files for further information.
-%% Copyright (c) 1991-1996 Kristoffer H. Rose <krisrose@brics.dk>
-%%
-%% The Xy-pic package is free software; you can redistribute it and/or modify
-%% it under the terms of the GNU General Public License as published by the
-%% Free Software Foundation; either version 2 of the License, or (at your
-%% option) any later version.
-%%
-%% The Xy-pic package is distributed in the hope that it will be useful, but
-%% WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
-%% or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
-%% for more details.
-%%
-%% You should have received a copy of the GNU General Public License along
-%% with this macro package; if not, write to the Free Software Foundation,
-%% Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-%%
-\ifx\xyloaded\undefined \input xy \fi
-
-\xyprovide{2cell}{Two-cell feature}{\stripRCS$Revision: 3.3 $}%
- {Ross Moore}{ross@mpce.mq.edu.au}%
- {Mathematics Department, Macquarie University, NSW~2109, Australia}
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\noindent
- This feature is designed to facilitate the typesetting of curved arrows,
- either singly or in pairs, together with labels on each part and between.
- The intended mathematical usage is for typesetting categorical ``2-cell''
- morphisms and ``pasting diagrams'', for which special features are provided.
- These features also allow attractive non-mathematical effects.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\paragraph*{Header:}\leavevmode
-\DOCHEADER
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- The 2-cell feature makes use of facilities from the `curve' extension
- which is therefore automatically loaded.
-
-\DOCMODE(
-\xyrequire{curve}\xycatcodes
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsection{Typesetting 2-cells in Diagrams}
-
-\noindent
-Categorical
-``2-cell'' morphisms are used in the study of tensor categories and elsewhere.
-The morphisms are displayed as a pair of curved arrows, symmetrically
-placed, together with an orientation indicated by a short broad arrow,
-or {\it Arrow}. Labels may be placed on all three components.
-
-\DOCMODE(
-\message{two-cells,}
-\DOCMODE)
-
-\UseAllTwocells
-
-\BUG: This document still uses version~2-style commmands, as described in
-appendix~??g[:v2].
-
-\xyrequire{v2}\xycatcodes
-
-\xymatrixcolsep{5pc}%
-\xymatrixrowsep{2pc}%
-
-\begin{code}
-\diagram
-A\rtwocell^f_g &B\\
-\enddiagram
-\end{code}
-$$ \docode $$
-\displaycode
-
-\begin{code}
-\diagram
-A\ruppertwocell^f{\alpha}
- \rlowertwocell_h{\beta}
- \rto_(.35)g & B\\
-\enddiagram
-\end{code}
-$$ \docode $$
-\displaycode
-
-These categorical diagrams frequently
-have a matrix-like layout, as with commutative diagrams.
-To facilitate this there are control sequences of the form:
-|\rtwocell| , |\ultwocell| , |\xtwocell| , \dots\
-analogous to the names defined in |xyv2| for use
-in diagrams produced using |xymatrix|.
-As this involves the definition of 21 new control sequences, many of which
-may never be used, these are not defined immediately upon loading |xy2cell|.
-Instead the user must first specify |\UseTwocells|.
-
-As in the second example above, just the upper or lower curved
-arrow may be set using control sequences of the form
-|\..uppertwocell| and |\..lowertwocell|.
-These together with the |\..compositemap| family, in which
-two abutting arrows are set with an empty object at the join,
-allow for the construction of complicated ``pasting diagrams''
-(see figure ??[f.pasting] for an example).
-
-The following initialise the families of control sequences
-for use in matrix diagrams.
-
-\begin{defs}
- |\UseTwocells| &\quad two curves \cr
- |\UseHalfTwocells| &\quad one curve \cr
- |\UseCompositeMaps| &\quad 2 arrows, end-to-end \cr
- |\UseAllTwocells| &\quad (all the above) \cr
-\end{defs}
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\DOCMODE(
-\xydef@\UseTwocells{\definesupermorphism{twocell}{%
- \xy@{start of 2-cell}{\begingroup}%
- \twocell@}}
-
-\xydef@\UseHalfTwocells{%
- \definesupermorphism{uppertwocell}{%
- \xy@{start of 2-cell}{\begingroup}%
- \uppertwocell@}%
- \definesupermorphism{lowertwocell}{%
- \xy@{start of 2-cell}{\begingroup}%
- \lowertwocell@}}
-
-\xydef@\UseCompositeMaps{\definesupermorphism{compositemap}{%
- \xy@{start composite-map}{\begingroup}%
- \compositemap@}}
-
-\xydef@\UseAllTwocells{%
- \UseTwocells \UseHalfTwocells \UseCompositeMaps }
-\DOCMODE)
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- The families of connections are defined using the utility macro\dots
-%
- |\definesupermorphism|
-%
- which defines control sequences for morphisms between
- neighbouring cells, and next-to-neighbouring cells.
-
- More distant cells use |\xtwocell|, |\xcompositemap|, etc.
- with <hop>s e.g.
- |\xtwocell[1,3]| and |\xtwocell[llddd]|.
-
-\DOCMODE(
-\xydef@\supermorphism#1[#2]#3{\def\afterMORPHISM{[#2]#3}#1}
-\xydef@\afterMORPHISM{}
-
-\xydef@\definesupermorphism#1#2{%
- \expandafter\def\csname x#1\endcsname{\supermorphism{#2}}%
- \expandafter\def\csname u#1\endcsname{\supermorphism{#2}[-1,0]{}}%
- \expandafter\def\csname d#1\endcsname{\supermorphism{#2}[1,0]{}}%
- \expandafter\def\csname l#1\endcsname{\supermorphism{#2}[0,-1]{}}%
- \expandafter\def\csname r#1\endcsname{\supermorphism{#2}[0,1]{}}%
- \expandafter\def\csname uu#1\endcsname{\supermorphism{#2}[-2,0]{}}%
- \expandafter\def\csname dd#1\endcsname{\supermorphism{#2}[2,0]{}}%
- \expandafter\def\csname ll#1\endcsname{\supermorphism{#2}[0,-2]{}}%
- \expandafter\def\csname rr#1\endcsname{\supermorphism{#2}[0,2]{}}%
- \expandafter\def\csname ur#1\endcsname{\supermorphism{#2}[-1,1]{}}%
- \expandafter\def\csname ul#1\endcsname{\supermorphism{#2}[-1,-1]{}}%
- \expandafter\def\csname dr#1\endcsname{\supermorphism{#2}[1,1]{}}%
- \expandafter\def\csname dl#1\endcsname{\supermorphism{#2}[1,-1]{}}%
- \expandafter\def\csname uul#1\endcsname{\supermorphism{#2}[-2,-1]{}}%
- \expandafter\def\csname uur#1\endcsname{\supermorphism{#2}[-2,1]{}}%
- \expandafter\def\csname ull#1\endcsname{\supermorphism{#2}[-1,-2]{}}%
- \expandafter\def\csname urr#1\endcsname{\supermorphism{#2}[-1,2]{}}%
- \expandafter\def\csname ddl#1\endcsname{\supermorphism{#2}[2,-1]{}}%
- \expandafter\def\csname ddr#1\endcsname{\supermorphism{#2}[2,1]{}}%
- \expandafter\def\csname dll#1\endcsname{\supermorphism{#2}[1,-2]{}}%
- \expandafter\def\csname drr#1\endcsname{\supermorphism{#2}[1,2]{}}%
- \expandafter\def\csname uull#1\endcsname{\supermorphism{#2}[-2,-2]{}}%
- \expandafter\def\csname uurr#1\endcsname{\supermorphism{#2}[-2,2]{}}%
- \expandafter\def\csname ddll#1\endcsname{\supermorphism{#2}[2,-2]{}}%
- \expandafter\def\csname ddrr#1\endcsname{\supermorphism{#2}[2,2]{}}}
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\bigskip
-
-Alternatively 2-cells can be set directly in \Xy-pictures without using the
-matrix feature. In this case the above commands are not needed. This is
-described in~\S??[standard].
-
-Furthermore a new directional |\dir{=>}| can be used to
-place an ``Arrow'' anywhere in a picture,
-after the direction has been established appropriately.
-It is used with all of the 2-cell types.
-
-\DOCMODE(
-\newdir{=>}{!/5pt/\dir{=}!/2.5pt/\dir{=}*!/-5pt/\dir2{>}}
-
-\xydef@\arrowobject#1{\def\Arrowobject@{#1}}
-\xydef@\Arrowobject@{\dir{=>}}
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-%{\obeylines\long\outer\gdef\Pastingexample{%
-\begin{code}
-\xymatrixrowsep{1.5pc}
-\xymatrixcolsep{3pc}
-\diagram
- & & \relax\rtwocell<0>^{f_3^{}\;\;}{\omit} & \relax\ddtwocell<0>{\omit}
- \drtwocell<0>^{\;\;f_4^{}}{<3>}
- \ddrrtwocell<\omit>{<8>}\\
- & & & &\relax\drtwocell<0>^{\;\;f_5^{}}{\omit}\\
-A \uurrcompositemap<2>_{f_1^{}}^{f_2^{}}{<.5>}
- \uurrlowertwocell<-6>{\omit}\relax
- \drtwocell<0>_{g_1^{}\;}{\omit}
- & & & \relax\urtwocell<0>{\omit}
- & &\relax\rtwocell<0>^{f_6^{}\;}{\omit}
- & \relax\rlowertwocell<-3>_{g_4^{}}{<-1>}
- \rcompositemap<6>_{f_7^{}}^{f_8^{}}{\omit} & B \\
- & \relax\urrtwocell<0>{\omit}
- \xcompositemap[-1,4]{}<-4.5>_{g_2^{}}^{g_3^{}}{\omit}\\
-\enddiagram
-\end{code}
-
-\begin{figure*}[bt]
-$$ \docode $$
-\caption{Pasting diagram.}
-??=[f.pasting]
-\end{figure*}
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\paragraph*{Default positions:}
-
- These set up default values for the parameters which
- specify the position of each component
- as well as the flags to indicate what type
- of 2-cell is to be typeset.
-
-\begin{defs1}
-\begin{tabular}{c l}
- |\toks6| &position of control point,
- normal to line $\overline{pc}$ at midpoint\\
- |\toks5| &position of central Arrow\\
- |\toks7| &position of |^| label\\
- |\toks8| &position of |_| label\\
- |\toks3| &flag for number of pieces... \\
- \quad |f| & \underline{f}ull: i.e. both curved arrows\\
- \quad |o| & \underline{o}ne: |\uppertwocell| or |\lowertwocell|\\
- \quad |t| & \underline{t}wo maps: |\compositemaps|\\
-\end{tabular}
-\end{defs1}
-
-\noindent
-|@| means to calculate from the value in |\toks6|, see |\tw@cell@@@|.
-
-\DOCMODE(
-\xydef@\twocell@{\toks6={3.5}\toks5={@}\toks7={@}\toks8={@}\toks3={f}%
- \tw@cell@ }
-\xydef@\uppertwocell@{\toks6={7}\toks5={@}\toks7={@}\toks8={@}\toks3={o}%
- \tw@cell@ }
-\xydef@\lowertwocell@{\toks6={-7}\toks5={@}\toks7={@}\toks8={@}\toks3={o}%
- \tw@cell@ }
-\xydef@\compositemap@{\toks6={3.5}\toks5={@}\toks7={@}\toks8={@}\toks3={t}%
- \tw@cell@ }
-\DOCMODE)
-
- This collects together all the relevant data, and resolves the
- default positions.
-
-\DOCMODE(
-\xydef@\tw@cell@@@{%
- \expandafter\ifx\the\toks6\omit\relax\toks6={}\else
-%
-% default position of label on upper arrow,
-% relative to where it meets the perpendicular bisector
-%
- \expandafter\ifx\expandafter @\the\toks7\relax\expandafter\dimen@\the\toks6\p@
- \expandafter\if\the\toks3t\relax\dimen@=\p@
- \else\expandafter\if\the\toks3o\divide\dimen@\tw@
- \ifdim\dimen@<\z@ \dimen@ii-\p@ \advance\dimen@ii\dimen@
- \dimen@=\dimen@ii \else \dimen@\p@ \fi
- \else\dimen@\p@
- \fi\fi
- \edef\tmp@{\expandafter\removePT@\the\dimen@}%
- \expandafter\toks\expandafter7\expandafter{\tmp@}\fi
-%
-% default position of label on lower arrow,
-% relative to where it meets the perpendicular bisector
-%
- \expandafter\ifx\expandafter @\the\toks8\relax
- \expandafter\dimen@\the\toks6\p@
- \expandafter\if\the\toks3t\relax\dimen@\p@
- \else\expandafter\if\the\toks3o\divide\dimen@\tw@
- \ifdim\dimen@<\z@ \dimen@ii-\p@ \advance\dimen@ii\dimen@
- \dimen@=\dimen@ii \else \dimen@\p@ \fi
- \else\dimen@\p@
- \fi\fi
- \edef\tmp@{\expandafter\removePT@\the\dimen@}%
- \expandafter\toks\expandafter8\expandafter{\tmp@}\fi
-%
-% default position of the Arrow, relative to midpoint
-%
- \expandafter\ifx\expandafter @\the\toks5\relax
- \expandafter\dimen@\the\toks6\p@
- \expandafter\if\the\toks3o\divide\dimen@ by-4\relax
- \else\dimen@\z@\fi
- \edef\tmp@{\expandafter\removePT@\the\dimen@}%
- \expandafter\toks\expandafter5\expandafter{\tmp@}\fi
- \fi
-%
-% possible modifications for module maps
-%
- \twocellmod@
-%
-% pass all the parameters to |\twocell@@@@|
-%
- \expandafter\if\the\toks3t\relax
-%
-% composed maps: ^ : first map _ : second map
-%
- \edef\tmp@{.[\noexpand\twocell@@@@{\the\toks6}{\the\toks5}%
- {\the\toks7}{\the\toks8}{\the\toks3}%
- {\the\toks2}{\the\toks1}{\the\toks@}{\the\toks4}!!!].\afterMORPHISM}%
- \else
-%
-% curved arrow(s)
-%
- \edef\tmp@{.[\noexpand\twocell@@@@{\the\toks6}{\the\toks5}%
- {\the\toks7}{\the\toks8}{\the\toks3}%
- {\the\toks1}{\the\toks2}{\the\toks@}{\the\toks4}!!!].\afterMORPHISM}%
- \fi
- \toks@={\endgroup}%
- \expandafter\def\expandafter\next@\expandafter{%
- \expandafter\def\expandafter\twocellhead@\expandafter{\twocellhead@}}%
- \expandafter\addtotoks@\expandafter{\next@}%
- \expandafter\def\expandafter\next@\expandafter{%
- \expandafter\def\expandafter\twocelltail@\expandafter{\twocelltail@}}%
- \expandafter\addtotoks@\expandafter{\next@}%
- \expandafter\addtotoks@\expandafter{\expandafter\twocellPATH\tmp@}%
- \the\toks@ }%
-\DOCMODE)
-
- See below for the possible forms of |\twocellPATH|.
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-Labels are placed labels on the upper and lower arrows,
-more correctly `anti-clockwise' and `clockwise', using |^| and |_|.
-These are entirely optional with the following token, or grouping, giving
-the contents of the label. When used with
-|\..compositemap| the |^| and |_| specify
-labels for the first and second arrows, respectively.
-
-\DOCMODE(
-\xydef@\twocellstyle{\scriptstyle}
-
-\xydef@\droptwocelllabel@#1{\xyFN@\droptwocelllabel@@#1@!}
-\xydef@\droptwocelllabel@@{%
- \ifx*\next\DN@*{\droptwocelldrop@}%
- \else\DN@##1@!{\droptwocelltext@{##1}}%
- \fi \next@ }
-
-{\xyuncatcodes \gdef\next#1{\drop+!C{\twocellstyle #1}}}
-\xylet@\droptwocelltext@=\next
-
-\xydef@\droptwocelldrop@#1@!{\bgroup \let\xy@=\oxy@
- \let\objectstyle=\twocellstyle \drop#1{}%
- \edef\tmp@{\egroup \X@min=\the\X@min \X@max=\the\X@max
- \Y@min=\the\Y@min \Y@max=\the\Y@max}\tmp@ }
-\DOCMODE)
-
-Normally the label is balanced text, set
-in \TeX's math mode, with |\twocellstyle| setting the style.
-The default definition is given by \dots
-
-|\def\twocellstyle{\scriptstyle}|
-
-\noindent
-This can be altered using |\def| in versions of \TeX\
-or |\redefine| in \LaTeX.
-However labels are not restricted to being simply text boxes.
-Any effect obtainable using the \Xy-pic kernel language can be set
-within an |\xybox| and used as a label. Alternatively if the first
-character in the label is |*| then the label is set as an
-\Xy-pic <object>, as if with |\drop<object>| or |*<object>| in
-the kernel language. The current direction is tangential to
-the curved arrows. Extra braces are needed to get a |*| as the label,
-as in |^{{{*}}}| or |_{{}*}|.
-
-The position of a label normal to the tangential direction
-can also be altered by {\em nudging} (see below).
-Although it is possible to specify multiple labels,
-only the last usage of each of |^| and |_| is actually set,
-previous specifications being ignored.
-
-Similarly a label for the central Arrow must be given,
-after the other labels, by enclosing it within braces |{...}|.
-An empty group |{}| gives an empty label; this is necessary
-to avoid misinterpretation of subsequent tokens. As above if the
-first character is |*| then the label is set as an \XY-pic <object>,
-the current direction being along the Arrow.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\paragraph*{Parsing:}
-
- Open a new group so the following registers can be used locally...
- |\toks@=\toks0|, |\toks1|, ..., |\toks8|
- the final parameter set is stored briefly in |\tmp@| before being used.
-
- OPTIONS:
-\begin{defs1}
-\begin{tabular}{c c l}
- && spaces are ignored \\
- |<| & |<num>| &determines position of curves control point\\
- & |<0>| &uses a single solid line,\\
- & |<\omit>| &causes only the central Arrow (with label) to be set\\
-\noalign{\smallskip}
- |\omit| &&omits the curved arrows, but allows their labels\\
- |^| &&place ``above'' label (more correctly ``anti-clockwise'')\\
- |_| &&place ``below'' label (more correctly ``clockwise'')\\
- |~'| &&change the arrowhead \\
- |~`| &&place/change the arrowtail\\
-\end{tabular}
-\end{defs1}
-
- Label data e.g. |^{#1}| |_{#1}|
- is stored temporarily in |\toks@| then passed via |\tw@@cell@@|
- to |\tw@cell@@| for further parsing, as: |\the\toks@ @|
-
- |~'| and |~`| change the values of |\twocellhead@| and |\twocelltail@|
- Normally |\twocelltail@| is |{}|, so |~`| also changes a flag to
- indicate that |\twocelltail@| is indeed required.
-
- When the next token is a grouping |{...}|
- then it gives the label for the central Arrow.
- No other label specifications may follow.
-
-
- Default head and tail ornaments...
-
-\DOCMODE(
-\xydef@\twocellhead#1{\def\twocellhead@{#1}}
-\xydef@\twocelltail#1{\def\twocelltail@{#1}}
-\xydef@\twocellhead@{\dir{>}}
-\xydef@\twocelltail@{}
-\DOCMODE)
-
- clear |\toks..| registers for the new connection labels.
-
-\DOCMODE(
-\xywarnifdefined\twocellmod@
-\xydef@\tw@cell@{\begingroup
- \toks@={{}}\toks1={{}}\toks2={{}}\toks4={{}}%
- \def\twocellmod@{}\xyFN@\tw@@cell@}%
-
-\xydef@\tw@@cell@{%
- \ifx\space@\next\expandafter\DN@\space{\xyFN@\tw@@cell@}%
- \else\ifx\bgroup\next \let\next@=\toks@\afterassignment\tw@@cell@@
- \else\ifx ^\next \DN@^##1{\toks@={##1}\nudgepos@71\tw@@cell@}%
- \else\ifx _\next \DN@_##1{\toks@={##1}\nudgepos@82\tw@@cell@}%
- \else\addLT@\ifx \next \addGT@{\addLT@\DN@##1}{%
- \toks6={##1}\ifx\omit##1\relax\toks3={t}\toks5={0}\fi\xyFN@\tw@@cell@}%
- \else\ifx\omit\next \DN@\omit{\omitarrows@\xyFN@\tw@@cell@}%
- \else\ifx~\next \DN@~{\xyFN@\whichCurveObject@}%
- \else \DN@{\xyFN@\tw@cell@@\empty @}%
- \fi\fi\fi\fi\fi\fi\fi%
- \next@ }
-
-\xydef@\whichCurveObject@{%
- \ifx\space@\next\expandafter\DN@\space{\xyFN@\whichCurveObject@}%
- \else\ifx\next^\DN@^##1{\xy@{~^{##1}}{\uppercurveobject{##1}}\xyFN@\tw@@cell@}%
- \else\ifx\next_\DN@_##1{\xy@{~_{##1}}{\lowercurveobject{##1}}\xyFN@\tw@@cell@}%
- \else\addRQ@\ifx\next \addRQ@\DN@##1{%
- \xy@{~'{##1}}{\def\twocellhead@{##1}}\xyFN@\tw@@cell@}%
- \else\addLQ@\ifx\next \addLQ@\DN@##1{%
- \xy@{~`{##1}}{\def\twocelltail@{##1}}\xyFN@\tw@@cell@}%
- \else\ifx!\next \DN@!{\xyFN@\checkmodmap@}%
- \else\ifx\next\bgroup\DN@##1{\xy@{~{##1}}{\curveobject{##1}}\xyFN@\tw@@cell@}%
- \else\DN@##1{\xy@{~##1}{\curveobject{##1}}\xyFN@\tw@@cell@}%
- \fi\fi\fi\fi \fi\fi\fi
- \next@ }
-
-\xydef@\checkmodmap@{%
- \ifx\space@\next\expandafter\DN@\space{\xyFN@\checkmodmap@}%
- \else \def\twocellmod@{\modmap@}%
- \ifx\next!\DN@!##1{%
- \xy@{~!!{##1}}{\def\modmapobject@{##1}}\xyFN@\tw@@cell@}%
- \else \DN@{\xyFN@\tw@@cell@}\fi
- \fi \next@ }
-\DOCMODE)
-
- With no arrows, still allow labels:
- default positions are at $0$, $+X$, $-X$, with $X=${\em default value}.
- These values are altered by ``nudging''.
-
-\DOCMODE(
-\xydef@\omitarrows@{\toks5={0}\toks6={}\toks7={0}\toks8={0}}
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\begin{figure*}[tp]
-\begin{syntax}
-%
-<twocell>
- &\iss & <2-cell><switches><Arrow>
- & typeset <2-cell> with the <switches> and <Arrow>
-\cr
-\noalign{\smallskip}
-%
-<2-cell> &\iss & |\..twocell|
- & typeset two curved arrows
-\cr
- &\orr & |\..uppertwocell|
- & typeset upper curved arrow only
-\cr
- &\orr & |\..lowertwocell|
- & typeset lower curved arrow only
-\cr
- &\orr & |\..compositemap|
- & use consecutive straight arrows
-\cr
-\noalign{\smallskip}
-%
-<Arrow> &\iss & |{|<tok><text>|}|
- & specifies orientation and label
-\cr
- &\orr & |{|<nudge><text>|}|
- & adjust position, use default orientation
-\cr
- &\orr & |{|<text>|}|
- & use default position and orientation
-\cr
- &\orr & |{|<tok>*<object>|}|
- & use <object> as the label
-\cr
- &\orr & |{|<nudge>*<object>|}| \orr |{|*<object>|}|
-\cr
-\noalign{\smallskip}
-%
-<tok> &\iss & |^| \orr |_| \orr |=|
- & oriented anti-/clockwise/equality
-\cr
- &\orr & |\omit|
- & no Arrow, default is clockwise
-\cr
- &\orr & |`| \orr |'| \orr |"| \orr |!|
- & no Arrow; tips on two curved arrows as:\\
- anti-/clockwise/double-headed/none
-\cr
-\noalign{\smallskip}
-%
-<switches> &\iss & <switch><switches>
- & list of optional modifications
-\cr
-\noalign{\smallskip}
-%
-<switch> &\iss & <empty>
- & use defaults
-\cr
-%
- &\orr & |^| <label>
- & place <label> on the upper arrow
-\cr
- &\orr & |_| <label>
- & place <label> on the lower arrow
-\cr
- &\orr & <nudge>
- & set the curvature, based on <nudge> value
-\cr
- &\orr & |\omit|
- & do not set the curved arrows
-\cr
- &\orr & \ |!|
- & place |\modmapobject| midway along arrows
-\cr
- &\orr & |~| <what> |{| <object> |}|
- & use <object> in place specified by <what>
-\cr
-\noalign{\smallskip}
-%
-<what> &\iss & <empty>
- & set curves using the specified <object>
-\cr
- &\orr & |^| \orr |_|
- & use <object> with upper/lower curve
-\cr
- &\orr & |`| \orr |'|
- & use <object> for arrow head/tail
-\cr
-%
-\noalign{\medskip}
-%
-<label> &\iss & <text>\ \orr\ <nudge> <text>
- & set <text>, displaced by <nudge>
-\cr
- &\orr & *<object>\ \orr\ <nudge>*<object>
- & set <object>, displaced by <nudge>
-\cr
-\noalign{\smallskip}
-%
-<nudge> &\iss & |<|<number>|>| & use <number> in an appropriate way,
- \eg, to position object or label along a fixed axis
-\cr
- &\orr & |<\omit>| & do not typeset the object/label
-\cr
-%
-\end{syntax}
-\caption{\protect<twocell\protect>s}
-??=[f.twocell]
-\end{figure*}
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsection{Standard Options}??=[Arrow]
-The orientation of the central Arrow may be reversed,
-turned into an equality, or omitted altogether.
-In each case a label may still be specified, so in effect the
-Arrow may be replaced by anything at all.
-
-These effects are specified by the first token in the central label,
-which thus has the form: |{|<tok><label>|}|
-where <tok> may be one of \dots
-
-\begin{defs1}
-\begin{tabular}{ c l }
- |_| & Arrow points clockwise \cr
- |^| & Arrow points anti-clockwise \cr
- |=| & no tip, denotes equality \cr
-|\omit|& no Arrow at all. \cr
-\end{tabular}
-\end{defs1}
-
-\noindent
-When none of these occurs then the default of |_| is assumed.
-If the label itself starts with one of these characters then
-specify |_| explicitly, or enclose the label within a group |{...}|.
-See {\em Extra Options~1}, for more values of <tok>.
-Also note that |*| has a special role when used as the first character;
-however it is considered to be part of the <label>, see above.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- OPTIONS for the central Arrow:
-
-\begin{defs}{c l}
- & ignore spaces\cr
- |^| & points anti-clockwise\cr
- |_| & points clockwise (default)\cr
- |=| & no |\Tip|, equality\cr
- |\omit|& no Arrow at all, just squine(s) or composed arrows\cr
- |'| & no Arrow, opposite squine reversed\cr
- |`| & no Arrow, forward squine reversed\cr
- |"| & no Arrow, tips on both ends\cr
- |!| & no Arrow, no tips on squines\cr
-\end{defs}
-
- the position of the Arrow is determined by ``nudging'' (see below)
- e.g.
- |{^<num>label}|, where the actual dimen is |<num>\xydashl@|
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\begin{code}
-\xymatrixcolsep{4pc}
-\xymatrixrowsep{1pc}
-\diagram
-A \rtwocell{_\alpha} & B \rtwocell{^\beta} &
-C \rtwocell{=\gamma} & D \rtwocell{\omit\Psi} & E \\
-\enddiagram
-\end{code}
-$$ \docode $$
-\displaycode
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\paragraph{Parsing of the Arrow's label}
-
-\DOCMODE(
-\xydef@\tw@@cell@@{\expandafter\xyFN@\expandafter\tw@cell@@\the\toks@ @}
-
-\xydef@\tw@cell@@{\ifx \space@\next\expandafter\DN@\space{\xyFN@\tw@cell@@}%
- \else\ifx ^\next
- \DN@^##1@{\toks@={##1}\toks4={^}\nudgepos@50\tw@cell@@@}%
- \else\addEQ@\ifx\next
- \addEQ@\DN@##1@{\toks@={##1}\toks4={=}\nudgepos@50\tw@cell@@@}%
- \else\ifx _\next
- \DN@_##1@{\toks@={##1}\toks4={_}\nudgepos@50\tw@cell@@@}%
- \else\addLT@\ifx \next
- \DN@##1@{\toks@={##1}\toks4={_}\nudgepos@50\tw@cell@@@}%
- \else\ifx\omit\next \DN@\omit##1@{\toks4={@}\toks@={##1}\tw@cell@@@}%
- \else\addRQ@\ifx\next \addRQ@\DN@##1@{\toks4={@}\toks3={/}\toks@={##1}%
- \nudgepos@50\tw@cell@@@}%
- \else\addLQ@\ifx\next \addLQ@\DN@##1@{\toks4={@}\toks3={b}\toks@={##1}%
- \nudgepos@50\tw@cell@@@}%
- \else\ifx"\next \DN@"##1@{\toks4={@}\toks3={B}\toks@={##1}%
- \nudgepos@50\tw@cell@@@}%
- \else\ifx!\next \DN@!##1@{\toks4={@}\toks3={@}\toks@={##1}%
- \nudgepos@50\tw@cell@@@}%
- \else\ifx\next\empty\DN@##1@{\toks@={{}}\toks4={_}\tw@cell@@@}%
- \else\DN@##1@{\toks@={##1}\toks4={_}\tw@cell@@@}%
- \fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi \next@ }
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsection{Nudging}
-Positions of all labels may be adjusted,
-as can the amount of curvature for the curved arrows.
-The way this is done is by specifying a ``nudge'' factor <num>
-at the beginning of the label.
-Here <num> is a number which specifies the actual position of the label
-in units of |\xydashl@| (the length of a single dash, normally 5pt)
-except with |\..compositemap|, see below.
-Movement is constrained to the perpendicular bisector
-of the line $\overline{cp}$.
-When nudging the label for the central Arrow
-it is the whole Arrow which is moved, along with its label.
-
-Curvature of the arrows themselves is altered by
-a nudge of the form |\..twocell|<num>....
-The separation of the arrows, along the bisector,
-is set to be <num>|\xydashl@|.
-When <num> is zero, that is |\..twocell<0>...|,
-the result is a single straight arrow,
-its mid-point being the origin for nudging labels.
-A negative value for <num> is also acceptable;
-but check the orientation on the Arrow
-and which of |^| and |_| correspond to which component.
-
-The origin for nudging labels is where the arrow
-crosses the bisector. Positive nudges move
-the label outwards while negative nudges move towards $\overline{pc}$
-and possibly beyond.
-The default position of a label is on the outside, with edge at the origin.
-
-The origin for nudging the Arrow is at the midpoint of $\overline{pc}$.
-A positive nudge moves in the clockwise direction.
-This will be the direction of the arrowhead,
-unless it has been reversed using |^|.
-
-\smallskip
-
-Labels on a |\..compositemap| are placed relative to the midpoint
-of the component arrows. Nudges are in units of 1pt.
-Movement is in the usual \Xy-pic {\em above} and {\em below} directions,
-such that a positive nudge is always outside the triangle formed
-by the arrows and line $\overline{pc}$.
-
-\medskip
-
-The special nudge value |<\omit>| typesets just the Arrow,
-omitting the curved arrows entirely.
-When used with labels, the nudge value |<\omit>| causes the following label
-to be ignored.
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\begin{exercise}
-Give code to typeset figure ??[f.pasting].
-
-\noindent
-Such code is relatively straight-forward, using ``nudging''
-and |\omit| to help position the arrows, curves and Arrows.
-It also uses an {\em excursion},
-as described below in the subsection {\em Extra Options~3}.
-
-% code from the earlier ``Pasting diagram'' example.
-%\Pastingexample\gdef\Pastingexample{}%
-%
-\begin{code}
-\xymatrixrowsep{1.5pc}
-\xymatrixcolsep{3pc}
-\diagram
- &&\relax\rtwocell<0>^{f_3^{}\;\;}{\omit}
- &\relax\ddtwocell<0>{\omit}
- \drtwocell<0>^{\;\;f_4^{}}{<3>}
- \ddrrtwocell<\omit>{<8>}\\
-&&&&\relax\drtwocell<0>^{\;\;f_5^{}}{\omit}\\
-A \uurrlowertwocell<-6>{\omit}\relax
-\uurrcompositemap<2>_{f_1^{}}^{f_2^{}}{<.5>}
- \drtwocell<0>_{g_1^{}\;}{\omit}
- &&&\relax\urtwocell<0>{\omit}
- &&\relax\rtwocell<0>^{f_6^{}\;}{\omit}
- &\relax\rlowertwocell<-3>_{g_4^{}}{<-1>}
- \rcompositemap<6>_{f_7^{}}^{f_8^{}}{\omit}
- & B \\
- &\relax\urrtwocell<0>{\omit}
- \xcompositemap[-1,4]{}%
- <-4.5>_{g_2^{}}^{g_3^{}}{\omit}\\
-\enddiagram
-\end{code}
-
-\answertext{Here is the code used to typeset the {\em pasting diagram} in
-figure~??g[xy2cell.doc:f.pasting].}
-\answercode
-\answertext\displaycode
-
-\answertext{\smallskip\noindent
-For the straight arrows, it would have been simpler to use |\..to|
-provided |xyarrow| has been loaded. Instead |\..twocell<0>...{\omit}|
-was used to illustrate the versatility of nudging and |\omit|;
-thus |xy2cell| can completely handle a wide range of diagrams,
-without requiring |xyarrow|. Note also the use of |\relax| at the start
-of each new cell, to avoid premature expansion of a complicated macro,
-which can upset the compiling mechanism.}
-\end{exercise}
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\paragraph{NUDGE } position of labels
-
-\DOCMODE(
-\xywarnifdefined\whichnudge
-\xywarnifdefined\whichinfo
-\xywarnifdefined\afternudge
-\xydef@\nudgepos@#1#2#3{\def\whichnudge{\toks#1}\def\whichinfo{\toks#2}%
- \def\afternudge{#3}\expandafter\xyFN@\expandafter\nudgepos@@\the\toks@ @}
-\DOCMODE)
-
-\begin{defs1}
-\begin{tabular}{c l}
- |#1| & which token register to store nudge amount\cr
- |#2| & which token register to store label\cr
- |#3| & what to do next, after parsing \cr
-\end{tabular}
-\end{defs1}
-
-\paragraph{Parsing: }
-%
- <num><label>|@|, <num> = nudge amount, as multiple of |\xydashl@|.
-
-\DOCMODE(
-\xydef@\nudgepos@@{\ifx \space@\next\expandafter\DN@\space{\xyFN@\nudgepos@}%
- \else\addLT@\ifx \next
- \addGT@{\addLT@\DN@##1}##2@{%
- \ifx\omit##1\relax\whichnudge={0}\whichinfo={}%
- \else\whichnudge={##1}\whichinfo={##2}\fi\xyFN@\afternudge}%
- \else \DN@##1@{\whichinfo={##1}\xyFN@\afternudge}%
- \fi\fi \next@ }
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsection{Extra Options}
-The following features are useful in non-mathematical applications.
-
-\subsubsection*{1. no Arrow}
-This is determined by special values for <tok> as the
-first (or only) character in the central label, as in the above
-description of the standard switches.
-
-\begin{defs1}
-\begin{tabular}{c l}
- |'| & arrowheads pointing clockwise;\cr
- |`| & arrowheads pointing anti-clockwise;\cr
- |"| & arrow tips on both ends;\cr
- |!| & no tips at all.\cr
-\end{tabular}
-\end{defs1}
-
-\noindent
-The central Arrow is omitted, leaving symmetrically placed
-curved connections with arrowheads at the specified ends.
-A label can be placed where the Arrow would have been.
-
-If a special arrowhead is specified using |~'{..}|
-(see Extra Options~2, below)
-then this will be used instead of the standard |\dir{>}|.
-
-\ifx\undefined\mathbf\def\mathbf{\boldmath}\fi
-\begin{code}
-\xymatrixcolsep{5pc}
-\diagram
- \relax\txt{Clouds }\rtwocell<10>
- _{\hbox{\tiny evaporation }}
- ^{\hbox{\tiny precipitation }}
-{'{\mathbf{H_2 O}}}
-&\relax\txt{Oceans}\\
-\enddiagram
-\end{code}
-$$ \docode $$
-\displaycode
-
-\begin{code}
-\xymatrixcolsep{5pc}
-\diagram
-\relax\txt{\llap{Math}ematics }\rtwocell
-_{\hbox{\tiny experiment }}
-^{\hbox{\tiny theory }}{"}
-& \relax\txt{Physics} \\
-\enddiagram
-\end{code}
-$$ \docode $$
-\displaycode
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsubsection*{2. Changing Tips and Module Maps }
-The following commands are provided for specifying the <object>
-to be used when typesetting various parts of the twocells.
-
-\medskip
-\noindent
-\begin{tabular}{l c}
-\noalign{\hrule}
-\noalign{\smallskip}
-{\em command} \hfill & {\em default} \cr
-\noalign{\smallskip}
-\noalign{\hrule}
-\noalign{\smallskip}
- |\modmapobject{|<object>|}| & |\dir{|$\vert$|}| \cr
- |\twocellhead{|<object>|}| & |\dir{>}| \cr
- |\twocelltail{|<object>|}| & |\dir{}| \cr
- |\arrowobject{|<object>|}| & |\dir{=>}| \cr
-\noalign{\smallskip}
- |\curveobject{|<object>|}| & \cr
- |\uppercurveobject{|<object>|}| & |{}| \cr
- |\lowercurveobject{|<object>|}| & |{}| \cr
-\noalign{\smallskip}
-\noalign{\hrule}
-\end{tabular}
-\medskip
-
-
-These commands set the object to be used for all subsequent
-2-cells at the same level of \TeX\ grouping.
-|\curveobject| specifies both of the upper- and lower-curve objects.
-For some of these there is also a way to change the object for the
-current 2-cell only.
-This requires a |~|-<switch> which is described below,
-except for the |\..curveobject| types, which are discussed in
-{\em Extra Options~4}.
-
-\medskip
-
-These effects are specified by placing switches
-after the |\..twocell| control sequence,
-\eg\ |\rtwocell| {\em switches\/} {\em labels\/}\dots~.
-Each switch is either a single token <tok>, or a
-|~|<tok> with a single argument: |~|<tok>|{|{\em arg\/}|}|.
-Possibilities are listed in the following table,
-in which |{..}| denotes the need for an argument.
-
-\begin{defs1}
-\begin{tabular}{c l}
- |\omit| & no arrows, Arrow and label only;\cr
- |!| & place module-map indicator;\cr
-|~'{..}| & change arrow-head to |{..}|;\cr
-|~`{..}| & place/change tail on arrow(s);\cr
-|~{..}| & change object used to set curves;\cr
-|~^{..}| & use object |{..}| to set upper curve;\cr
-|~_{..}| & use object |{..}| to set lower curve;\cr
-\end{tabular}
-\end{defs1}
-
-\noindent
-Here we discuss the use of |!|, |~'|, |~`| and |\omit|.
-The description of |~^|, |~_| and |~{..}| is given in {\em Extra Options~4}.
-
-\medskip
-The default module map indicator places a single
-dash crossing the arrow at right-angles,
-located roughly midway along the actual printed portion of the arrow,
-whether curved or straight.
-This takes into account the sizes of the objects being connected,
-thereby giving an aesthetic result when these sizes differ markedly.
-This also works with |\..compositemap| where an indicator is placed
-on each arrow. The actual object can be changed using |\modmapobject|.
-
-\medskip
-Any of the standard \Xy-pic tips may be used for arrow-heads.
-This is done using |~'{..}|,
-for example |~'{\dir{>>}}| gives double-headed arrows.
-Similarly |~`{..}| can be used to place an arrow-tail.
-Normally the arrow-tail is {}, so is not placed;
-but if a non-empty tail has been specified then it will
-be placed, using |\drop|.
-No guarantee is offered for the desired result being obtained
-when an arrow-tail is mixed with the features of {\em Extra Options~1}.
-
-\begin{code}
-\modmapobject{\objectbox{\otimes}}
-\xymatrixcolsep{5pc}
-\diagram
-P\rtwocell~!~'{\dir{>>}}~`{\dir{|}}
- ^{<1.5>M}_{<1.5>M'}{=f} & S \\
-\enddiagram
-\end{code}
-$$ \docode $$
-\displaycode
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- switch for module maps...
- ...places decoration called |\modmapobject| half way along arrows
-
-\DOCMODE(
-\xydef@\modmap@{%
- \expandafter\ifx\the\toks4@\toks4={!}%
- \else\expandafter\ifx\the\toks4=\toks4={H}%
- \else\expandafter\ifx\the\toks4^\toks4={A}%
- \else\expandafter\ifx\the\toks4_\toks4={V}\fi\fi\fi\fi
- \expandafter\DN@\expandafter{\the\toks6}%
- \ifx\next@\empty\relax\else\expandafter\moddefs@\fi}
-\DOCMODE)
-
- also adjust curvature and label positions
-
-\DOCMODE(
-\xydef@\moddefs@{%
- \expandafter\dimen@\the\toks6\p@
- \ifdim\dimen@=\z@\relax
- \expandafter\dimen@\the\toks7\p@
- \ifdim\dimen@<\z@\advance\dimen@.5\p@\else\advance\dimen@-.5\p@\fi
- \edef\tmp@{\noexpand\toks7={\expandafter\removePT@\the\dimen@}}\tmp@
- \expandafter\dimen@\the\toks8\p@
- \ifdim\dimen@<\z@\advance\dimen@-.5\p@\else\advance\dimen@.5\p@\fi
- \expandafter\ifx\the\toks3t\advance\dimen@-1\p@\fi
- \edef\tmp@{\noexpand\toks8={\expandafter\removePT@\the\dimen@}}\tmp@
- \else
- \ifdim\dimen@<\z@\advance\dimen@-.5\p@\else\advance\dimen@.5\p@\fi
- \edef\tmp@{\noexpand\toks6={\expandafter\removePT@\the\dimen@}}\tmp@
-% \expandafter\dimen@\the\toks5\p@
-% \ifdim\dimen@<\z@\advance\dimen@-.5\p@\else\advance\dimen@.5\p@\fi
-% \edef\tmp@{\noexpand\toks5={\expandafter\removePT@\the\dimen@}}\tmp@
- \expandafter\dimen@\the\toks7\p@
- \ifdim\dimen@<\z@\advance\dimen@-.5\p@\else\advance\dimen@.5\p@\fi
- \expandafter\ifx\the\toks3t\advance\dimen@-2\p@\fi
- \edef\tmp@{\noexpand\toks7={\expandafter\removePT@\the\dimen@}}\tmp@
- \expandafter\dimen@\the\toks8\p@
- \ifdim\dimen@<\z@\advance\dimen@-.5\p@\else\advance\dimen@.5\p@\fi
- \expandafter\ifx\the\toks3t\advance\dimen@-2\p@\fi
- \edef\tmp@{\noexpand\toks8={\expandafter\removePT@\the\dimen@}}\tmp@
- \fi }%
-
-%\def\moddefs@{}
-\DOCMODE)
-
- default object is |\stop|, user can change this with |\modmapobject#1|
-
-\DOCMODE(
-\xydef@\modmapobject#1{\def\modmapobject@{#1}}
-\xydef@\modmapobject@{\dir{|}}
-\xydef@\@modmapobject@{{\if\@mod@\relax\expandafter\empty
- \else\expandafter\modmapobject@\fi}}
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsubsection*{3. Excursions}
-Syntax for |\xcompositemap| and |\x..twocell| types
-is a little different to
-what might be expected from that for |\xto|, |\xline|, etc.
-For example,
-%
-\begin{defs1}
-|\xtwocell[|<hop>|]{|<displace>|}...|
-\end{defs1}
-%
-\noindent
-connects to the <pos> displaced by <displace> from
-the relative cell location specified by <hop>.
-The displacement can be any string of valid \Xy-pic commands,
-but they must be enclosed within a group |{...}|.
-When the cell location is the target,
-a~null grouping |{}| {\em must} be given.
-
-When used with the |<\omit>| nudge, such excursions allow a labelled Arrow
-to be placed anywhere within an \Xy-pic diagram;
-furthermore the Arrow can be oriented to point in any direction.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\DOCMODE(
-\xydef@\curveobject#1{\def\ucurveObject@{~*#1}\def\dcurveObject@{~*#1}}
-\xydef@\uppercurveobject#1{\def\ucurveObject@{~*#1}}
-\xydef@\lowercurveobject#1{\def\dcurveObject@{~*#1}}
-\xydef@\ucurveObject@{}
-\xydef@\dcurveObject@{}
-\DOCMODE)
-
-The empty object gives the default of closely spaced tiny dots,
-resulting in a ``smooth'' curve.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-The following macro is used in conjunction with compiling diagrams,
-to include the global parameters in the compiled file.
-
-\DOCMODE(
-\xydef@\savetwocellobjects{%
- \xy@{twocell objects}{%
- \expandafter\uppercurveobject\expandafter{\ucurveObject@}%
- \expandafter\lowercurveobject\expandafter{\dcurveObject@}%
- \expandafter\modmapobject\expandafter{\modmapobject@}%
- \expandafter\twocellhead\expandafter{\twocellhead@}%
- \expandafter\twocelltail\expandafter{\twocelltail@}%
- \expandafter\arrowobject\expandafter{Arrowobject@}%
- }}
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsubsection*{4. Fancy curves}
-By specifying |\curveobject| an arbitrary object may be used to
-construct the curved arrows. Indeed with a
-|\..twocell| different objects can be used with
-the upper and lower curves by specifying
-|\uppercurveobject| and |\lowercurveobject|.
-
-These specifications apply to all 2-cells subsequently constructed at
-the same level of \TeX\ grouping.
-Alternatively using a |~|-switch, as in {\em Extra Options~2},
-allows such a specification for a single 2-cell or curved part.
-
-Objects used to construct curves can be of two types.
-Either a single <object> is set once, with copies placed along the curve.
-Alternatively a directional object can be aligned with
-the tangent along the curve. In this case use a specification takes the
-form:
-
-|\curveobject{|<spacer>|~**|<object>|}|.
-
-\noindent
-Here <spacer> may be any <object> of non-zero size.
-Typically it is empty space, \eg\ |+|<dimen>|{}|.
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\begin{exercise}
-Give code to typeset the following diagrams.
-
-\begin{code}
-{\uppercurveobject{{?}}
- \lowercurveobject{{\circ}}
-\xymatrixcolsep{5pc}
-\xymatrixrowsep{2pc}
-\diagram
- \relax\txt{ FUn }\rtwocell<8>{!\&}
- & \relax\txt{ gaMES }
- \enddiagram}
-\end{code}
-$$\docode$$
-
-\answertext{Here is the code
-used by the author to set the first diagram.}
-\answercode
-\answertext\displaycode
-
-\begin{code}
-\xymatrixcolsep{2.5pc}
-\xymatrixrowsep{4pc}
-\diagram
- \relax\txt<1.5cm>{\bf Ground State}
- \rrtwocell<12>~^{+{}~**!/-2.5pt/\dir{>}}
- ~_{++{}~**!/5pt/\dir{<<}}
- ^{<1.5>\txt{\small continuous power}}
- _{<1.5>\txt{\small pulsed emission}}{!}
-& \relax\;\; N\!i\,C\!d\;\; \Circled
-& \relax\txt<1.50cm>{\bf Excited State}
-\enddiagram
-\end{code}
-$$\docode$$
-
-\answertext{Here is the code
-used for the second diagram.}
-\answercode
-\answertext\displaycode
-
-\end{exercise}
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsection{After Parsing...}
-
- Values for |\twocellPATH|, depends on the mode of picture/diagram
- as to whether the |@c| and |@p| are known yet, or still have
- to be read.
-
-\DOCMODE(
-\xydef@\twocell@path.[#1].{%
- \expandafter\ifx\csname Q@@c\endcsname\relax
- \DN@{\enter@{\cfromthec@ \pfromthep@ \basefromthebase@}%
- \xy@{}{\expandafter\edef\csname Q@@\endcsname{\cfromthec@}}%
- \afterPOS{\xy@{}%
- {\expandafter\edef\csname Q@@c\endcsname{\cfromthec@}}%
- \xy@{}%
- {\cfromid@{@}\expandafter\edef\csname Q@@p\endcsname{\cfromthec@}}%
- \xy@{twocell #1}{#1}\leave@\aftertwoCELL};p,}%
- \else
- \DN@{\enter@{\cfromthec@ \pfromthep@ \basefromthebase@}%
- \xy@{twocell #1}{#1}\leave@\aftertwoCELL}%
- \fi \next@ }
-
-\xydef@\twocellpath.[#1].{%
- \expandafter\edef\csname Q@@p\endcsname{\cfromthec@}%
- \xy@{}{\enter@{\pfromthep@}}%
- \xy@{}{\enter@{\cfromthec@ \pfromthep@ \basefromthebase@}%
- \enter@{\pfromthec@}}%
- \afterPOS{\xy@{}{\leave@\setupDirection@}#1\restore\restore
- \xy@{end of 2-cell}\xysaveMinMax@ }}%
-
-\xydef@\xysaveMinMax@{\edef\tmp@{\endgroup
- \noexpand\ifdim\X@max<\the\X@max \X@max=\the\X@max\noexpand\fi
- \noexpand\ifdim\X@min>\the\X@min \X@min=\the\X@min\noexpand\fi
- \noexpand\ifdim\Y@max<\the\Y@max \Y@max=\the\Y@max\noexpand\fi
- \noexpand\ifdim\Y@min>\the\Y@min \Y@min=\the\Y@min\noexpand\fi
- }\tmp@ }
-\DOCMODE)
-
-\DOCMODE(
-\xylet@\twocellPATH=\twocellpath
-\xydef@\aftertwo@CELL{\let\twocellPATH=\twocellpath \def\aftertwoCELL{}}
-\xydef@\aftertwoCELL{}
-\DOCMODE)
-
- It remains to collect everything together and place it on the queue.
-
-\DOCMODE(
-\xydef@\twocell@@@@#1!!!{\xy@{twocell #1}{\twocell@@#1!!!}}
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\subsection{2-cells in general \Xy-pictures}
-??=[standard]
-Two-cells can also be set directly within any \Xy-picture, without the
-matrix feature, using either |\drop| or |\connect|.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\DOCMODE(
-\let\xystatus=\xystatus@
-\xydef@\twocell{\hbox\bgroup\@twocell}
-\xydef@\uppertwocell{\hbox\bgroup\@uppertwocell}
-\xydef@\lowertwocell{\hbox\bgroup\@lowertwocell}
-\xydef@\compositemap{\hbox\bgroup\@compositemap}
-
-\xydef@\twocelll#1#{\hbox\bgroup\xy@\save\save@\@twocelll{#1}}
-\xydef@\@twocelll#1#2{%
- \afterPOS{\@twocelll@\xyFN@\twocell@#1{#2}}}
-
-\xydef@\uppertwocelll#1#{\hbox\bgroup\xy@\save\save@\@uppertwocelll{#1}}
-\xydef@\@uppertwocelll#1#2{%
- \afterPOS{\@twocelll@\xyFN@\uppertwocell@#1{#2}}}
-
-\xydef@\lowertwocelll#1#{\hbox\bgroup\xy@\save\save@\@lowertwocelll{#1}}
-\xydef@\@lowertwocelll#1#2{%
- \afterPOS{\@twocelll@\xyFN@\lowertwocell@#1{#2}}}
-
-\xydef@\compositemapp#1#{\hbox\bgroup\xy@\save\save@\@compositemapp{#1}}
-\xydef@\@compositemapp#1#2{%
- \afterPOS{\@twocelll@\xyFN@\compositemap@#1{#2}}}
-%
-\xydef@\@twocelll@{%
-% \idfromc@{@c}\swap@\idfromc@{@p}\swap@
- \expandafter\edef\csname Q@@c\endcsname{\cfromthec@}\swap@
- \expandafter\edef\csname Q@@p\endcsname{\cfromthec@}\swap@
- \let\twocellPATH=\twocell@path
-% \def\aftertwoCELL{\twocell@DONE}}
- \def\aftertwoCELL{\twocell@DONE \xy@\restore \leave@
-% \cfromid@{@c}\no@@ \xystatus@{end: }
- }}
-
-\xydef@\@twocell#1{\DN@{\@twocell@\twocell@}\xyFN@\next@[#1]}
-\xydef@\@uppertwocell#1{\DN@{\@twocell@\uppertwocell@}\xyFN@\next@[#1]}
-\xydef@\@lowertwocell#1{\DN@{\@twocell@\lowertwocell@}\xyFN@\next@[#1]}
-\xydef@\@compositemap#1{\DN@{\@twocell@\compositemap@}\xyFN@\next@[#1]}
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\begin{code}
-\def\myPOS#1{\POS}\def\goVia#1{%
- \afterPOS{\connect#1\myPOS}}
-\xy
- *+{A}="A",+<1cm,1.5cm>*+{B}="B",
- +<2.0cm,0pt>*+{C}="C",
- +<1cm,-1.5cm>*+{D}="D",
-"A";\goVia{\uppertwocell^\alpha{}}"B"{}
-;\goVia{\twocell^\zeta_\xi{\gamma}}"C"{}
-;\goVia{\compositemap{}}"D"{},
-"A";\goVia{\lowertwocell{}}"D"{}
-\endxy
-\end{code}
-
-\displaycode
-%\begin{figure}[hbt]
-$$\docode$$
-%??=[f.xypic]
-%\caption{2-cells in \protect\Xy-pictures}
-%\end{figure}
-
-\begin{code}
-\xy *+{A}="A",+<1cm,1.5cm>*+{B}="B",
- +<2cm,0pt>*+{C}="C",
- +<1cm,-1.5cm>*+{D}="D",
-"A";"B",{\uppertwocell^\alpha{}},
-"B";"C",{\twocell^\zeta_\xi{\gamma}},
-"C"; \afterPOS{\drop\compositemap{}}"D"
-\POS "A";
- \afterPOS{\drop\lowertwocell{}}"D"
-\endxy
-\end{code}
-
-The code shown is a compact way to place a chain
-of 2-cells within a picture.
-It illustrates a standard technique for using
-|\afterPOS| to find a <pos> to be used for part of
-a picture, then subsequently reuse it.
-Also it is possible to use |\drop| or <decor>s
-to specify the 2-cells, giving the same picture.
-
-\displaycode
-
-The |\connect| variant is usually preferable
-as this maintains the size of the object at $c$,
-while the |\drop| variant leaves
-a rectangular object having $p$ and $c$ on opposite sides.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- This is used outside of diagrams.
-
-\DOCMODE(
-\xydef@\@twocell@#1{\ifx\next[\DN@[{\toks@={#1}\xyFN@\@@twocell@}%
- \else\DN@{#1{}}\fi
-%%
-% \idfromc@{@c}\swap@\idfromc@{@p}\swap@
- \expandafter\edef\csname Q@@c\endcsname{\cfromthec@}\swap@
- \expandafter\edef\csname Q@@p\endcsname{\cfromthec@}\swap@
- \let\twocellPATH=\twocell@path
- \def\aftertwoCELL{\twocell@DONE}\next@}
-\DOCMODE)
-
-This hack is necessary, since |\DN@[##1]{#1##1}| will strip braces.
-
-\DOCMODE(
-\xydef@\@@twocell@{\ifx\next\bgroup\DN@##1]{\the\toks@{##1}}%
- \else\DN@##1]{\the\toks@##1}\fi\next@}
-\DOCMODE)
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\TODO:
- These are supposed to allow |\dir\...twocell{...}| to work.
- At present it seems to be impossible to do this.
-
-\DOCMODE(
-% \expandafter\xydefcsname@\expandafter{\codeof\twocell}{\@twocell}
-% \expandafter\xydefcsname@\expandafter{\codeof\uppertwocell}{\@uppertwocell}
-% \expandafter\xydefcsname@\expandafter{\codeof\lowertwocell}{\@lowertwocell}
-% \expandafter\xydefcsname@\expandafter{\codeof\compositemap}{\@compositemap}
-%% \DN@{\twocell}%
-%% \expandafter\def\csname*dir@@\codeof\next@ @\endcsname{\@twocell}
-%% \DN@{\uppertwocell}%
-%% \expandafter\def\csname*dir@@\codeof\next@ @\endcsname{\@uppertwocell}
-%% \DN@{\lowertwocell}%
-%% \expandafter\def\csname*dir@@\codeof\next@ @\endcsname{\@lowertwocell}
-%% \DN@{\compositemap}%
-%% \expandafter\def\csname*dir@@\codeof\next@ @\endcsname{\@compositemap}
-\DOCMODE)
-
-...since the contents of |{..}| is variable.
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- Finish off the box, set up the object size,
- establish the |\Drop@@| and |\Connect@@| methods.
-
-\DOCMODE(
-\xydef@\twocell@DONE{%
- \edef\tmp@{\egroup \X@min=\the\X@min \X@max=\the\X@max
- \Y@min=\the\Y@min \Y@max=\the\Y@max}\tmp@
- \L@c=\X@c \advance\L@c-\X@min \R@c=\X@max \advance\R@c-\X@c
- \D@c=\Y@c \advance\D@c-\Y@min \U@c=\Y@max \advance\U@c-\Y@c
- \ht\z@=\U@c \dp\z@=\D@c \dimen@=\L@c \advance\dimen@\R@c \wdz@=\dimen@
- \computeLeftUpness@
-%
-\setboxz@h{\kern-\X@p \raise-\Y@c\boxz@ }%
-\dimen@=\L@c \advance\dimen@\R@c \wdz@=\dimen@ \ht\z@=\U@c \dp\z@=\D@c
-%
- \Edge@c={\rectangleEdge}\Invisible@false \Hidden@false
- \edef\Drop@@{\noexpand\drop@Twocell
- \noexpand\def\noexpand\Leftness@{\Leftness@}%
- \noexpand\def\noexpand\Upness@{\Upness@}}%
- \edef\Connect@@{\noexpand\connect@Twocell
- \noexpand\ifdim\X@max<\the\X@max \X@max=\the\X@max\noexpand\fi
- \noexpand\ifdim\X@min>\the\X@min \X@min=\the\X@min\noexpand\fi
- \noexpand\ifdim\Y@max<\the\Y@max \Y@max=\the\Y@max\noexpand\fi
- \noexpand\ifdim\Y@min>\the\Y@min \Y@min=\the\Y@min\noexpand\fi }}%
-\DOCMODE)
-
- modified |\Drop@@| and |\Connect@@|
-
-\DOCMODE(
-\xydef@\drop@Twocell{\boxz@ }
-
-\xydef@\connect@Twocell{%
- \setboxz@h{\kern\X@p \raise\Y@c\box\lastobjectbox@ }%
- \wdz@=\z@ \ht\z@=\z@ \dp\z@=\z@ \Drop@@ }
-\DOCMODE)
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-|\twocell@@| is the main switching engine, taking 9 parameters determining
- which pieces to set and where to position them. This includes
- curvature of the squines, whether to draw two squines
- or only one, or to use straight lines,
- whether to have a central Arrow and its orientation,
- contants of labels and their positions.
-
- The current p and c are the extents of the connection
- these are stored as |"@p"| and |"@c"| for repeated use;
-
-\begin{defs1}
-\begin{tabular}{c l}
- |#1| & determines location of control point |"@m"|\cr
- |#2| & location of |=>|, as multiple of |\xydashl@| from |"@m"|\cr
- |#3| & location of |_| label (source arrow)\cr
- |#4| & location of |^| label (target arrow)\cr
- |#5| & flag for how many squines to draw \& which tips\cr
- |#6| & label for source arrow\cr
- |#7| & label for target arrow\cr
- |#8| & label for |=>| (2-cell morphism)\cr
- |#9| & determines orientation of 2-cell \cr
-\end{tabular}
-\end{defs1}
-
-The following tokens may appear as parameters in |#9|:
-|!|, |^|, |_|, |=|, |A|, |V|, |H|
-
-\DOCMODE(
-\xywarnifdefined\@mod@
-\xywarnifdefined\Arrowtok@
-
-\xydef@\twocell@@#1#2#3#4#5#6#7#8#9!!!{%
- \def\@mod@{@}\DN@{#9}%
- \ifx #9!\def\Arrowtok@{@}\else\ifx #9A\def\Arrowtok@{^}%
- \else\ifx #9V\def\Arrowtok@{_}\else\ifx #9H\def\Arrowtok@{=}%
- \else\def\@mod@{\relax}%
- \ifx #5/\def\Arrowtok@{@}\else\ifx #5b\def\Arrowtok@{@}%
- \else\ifx #5B\def\Arrowtok@{@}\else\ifx #5@\def\Arrowtok@{@}%
- \else\def\Arrowtok@{#9}%
- \fi\fi\fi\fi\fi\fi\fi\fi
- \addEQ@\ifx #9\def\Arrowtok@{=}\fi
- \DN@{\omit}\ifx\next@\Arrowtok@\def\Arrowtok@{}\else
- \edef\Arrowtok@{\codeof\Arrowtok@}\fi
- \save@ \idfromc@{@c}\swap@\idfromc@{@p}\swap@
- \cfromid@{@c}\no@@
-%
- \ifdim \X@c<\X@p \X@min=\X@c \X@max=\X@p \else \X@min=\X@p \X@max=\X@c \fi
- \ifdim \Y@c<\Y@p \Y@min=\Y@c \Y@max=\Y@p \else \Y@min=\Y@p \Y@max=\Y@c \fi
-%
- \Calong@@{.5}\idfromc@{@m}\idfromc@{@m1}\idfromc@{@m2}%
-%
- \ifx #5t\relax
- \enter@{\cplusthec@\pfromthep@}%
- \enter@\DirectionfromtheDirection@ \begingroup\aboveDirection@ \xydashl@
- \DN@{#1}\ifx\next@\empty\dimen@=\z@\else\dimen@=#1\p@\fi
- \ifdim\dimen@=\z@ \DN@{\vfromslide@i{\xydashl@}@}\relax
- \else\DN@{\vfromslide@i{#1\xydashl@}@}\fi \next@
- \czeroEdge@ \leave@ \no@@ \drop@{+}{}\idfromc@{@m1}%
- \DN@{#1}\ifx\next@\empty\DN@{\no@@}\else\DN@{\connect@{\dir}{-}}\fi
- \else
- \DN@{#1}\ifx\next@\empty\dimen@=\z@\else\dimen@=#1\p@\fi
- \ifdim\dimen@=\z@ \enter@{\cplusthec@\pfromthep@}%
- \enter@\DirectionfromtheDirection@ \begingroup\aboveDirection@\xydashl@
- \vfromslide@i{\xydashl@}@\czeroEdge@ \leave@ \idfromc@{@m1}%
- \cfromid@{@p}\swap@\cfromid@{@c}%
- \DN@{#1}\ifx\next@\empty\DN@{\no@@}\else\DN@{\connect@{\dir}{-}}\fi
- \else \DN@{\enter@\cplusthec@
- \enter@\DirectionfromtheDirection@ \begingroup\aboveDirection@ \xydashl@
- \vfromslide@i{#1\xydashl@}@\czeroEdge@ \leave@
- \idfromc@{@m1}\cfromid@{@p}\swap@\cfromid@{@c}%
- \edef\next@{\codeof\ucurveObject@}%
- \ifx\next@\empty\DN@{\connect@\crv{"@m1"}}%
- \else
- \DNii@####1{\connect@\crv{####1}}\expandafter\DN@\expandafter{%
- \expandafter\nextii@\expandafter{\ucurveObject@"@m1"}}%
- \fi \next@ }%
-%% \ifx\next@\empty\def\ucurveObject@{.}\fi
-%% \enter@\cfromthec@\sinit@\cfromid@{@m1}\senter@\leave@
-%% \expandafter\connect@\expandafter\crvs\expandafter{\ucurveObject@}%
-%% \sinit@\sleave@ }%
- \fi
- \fi \next@
-%
- \DN@{#1}\ifx\next@\empty\relax\else
- \if\@mod@ @\relax
- \enter@\pfromthep@ \Creset@@
- \ifx #5t\relax
- \PLACEedgec@ \PLACEedgep@ \def\PLACEf@{{.5}}%
- \else \def\next@{\crvreset@}%
- \ifx\next@\Creset@@
- \gettwocelledges@ \edef\PLACEf@{{\expandafter\removePT@\the\dimen@}}%
- \else \PLACEedgec@ \PLACEedgep@ \def\PLACEf@{{.5}}\fi
- \fi
- \expandafter\Calong@@\PLACEf@ \czeroEdge@ \leave@
- \edef\tmp@{\codeof\modmapobject@}%
- \ifx\tmp@\empty \DN@{\drop@{\dir}{|}}%
- \else \DNii@##1##{\drop@{##1}}%
- \DN@{\expandafter\nextii@\modmapobject@{}}%
- \fi \next@
- \fi\fi
-%
- \DN@{#6}\ifx\next@\empty\DN@{\relax}\else
- \DNii@{{}}\ifx\next@\nextii@\DN@{\relax}\else
- \ifx @#3\relax\DN@{\relax}\else
- \DN@{\enter@\pfromthep@ \Creset@@
- \Calong@@{.5}\czeroEdge@ \leave@
- \enter@\cplusthec@
- \enter@\DirectionfromtheDirection@\begingroup
- \DN@{#1}\ifx\next@\empty\dimen@\z@\else\dimen@=#1\p@\fi
- \ifdim\dimen@<\z@ \belowDirection@ \xydashl@
- \else \aboveDirection@ \xydashl@ \fi
-% \vfromslide@i{#3\xydashl@}@\czeroEdge@ \leave@
-% \droptwocelllabel@{#6}}%
- \dimen@=#3\p@ \if\@mod@ @\relax
- \advance\dimen@\ifdim\dimen@<\z@-\fi.5\p@\fi
- \edef\next@{\expandafter\removePT@\the\dimen@}%
- \expandafter\vfromslide@i\expandafter{\next@\xydashl@}@\leave@
- \droptwocelllabel@{#6}}%
- \fi\fi\fi \next@
-%
-%
- \DN@{#1}\ifx\next@\empty\relax\else
- \ifx #5b\relax % tip at start only
- \enter@ {\pfromthep@ }\Creset@@ \PLACEedgep@
- \Calong@@{0}\czeroEdge@ \leave@
- \edef\next@{\codeof\twocelltail@}%
- \ifx\next@\empty \DN@{\dir{>}}%
- \ifx\next@\twocellhead@\drop@{\dir}{<}%
- \else
- \reverseDirection@ \DNii@##1##{\drop@{##1}}%
- \expandafter\nextii@\twocellhead@{}\reverseDirection@
- \fi
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocelltail@{}%
- \fi
- \else\ifx #5@\relax % no tips at all
- \else % tip at end...
- \enter@\pfromthep@ \Creset@@ \PLACEedgec@
- \Calong@@{1}\czeroEdge@ \leave@
- \edef\next@{\codeof\twocellhead@}%
- \ifx\next@\empty\drop@{\dir}{>}%
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocellhead@{}%
- \fi
- \ifx #5B\relax % ... and also at start.
- \enter@ {\pfromthep@ }\Creset@@ \PLACEedgep@
- \Calong@@{0}\czeroEdge@ \leave@
- \edef\next@{\codeof\twocelltail@}%
- \ifx\next@\empty \DN@{\dir{>}}%
- \ifx\next@\twocellhead@\drop@{\dir}{<}%
- \else
- \reverseDirection@\DNii@##1##{\drop@{##1}}%
- \expandafter\nextii@\twocellhead@{}\reverseDirection@
- \fi
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\drop\twocelltail@{}%
- \fi
- \else\ifx #5/\relax
- \else \edef\next@{\codeof\twocelltail@}%
- \ifx\next@\empty\relax\else
- \enter@\pfromthep@ \Creset@@ \PLACEedgep@
- \Calong@@{0}\czeroEdge@ \leave@
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocelltail@{}%
- \fi\fi\fi
- \fi\fi\fi
-%
- \cfromid@{@p}\swap@\cfromid@{@c}\no@@ \cfromid@{@m}%
- \ifx #5t\relax
- \idfromc@{@m2}\cfromid@{@m1}\swap@ \cfromid@{@c}\no@@
- \DN@{#1}\ifx\next@\empty\DN@{\no@@}\else\DN@{\connect@{\dir}{-}}\fi
- \else\ifx #5o\relax
- \idfromc@{@m2}\DN@{}%
- \else % second curved arrow
- \DN@{#1}\ifx\next@\empty\dimen@=\z@\else\dimen@=#1\p@\fi
- \ifdim\dimen@=\z@
- \enter@{\cplusthec@\pfromthep@}%
- \enter@\DirectionfromtheDirection@ \begingroup \belowDirection@\xydashl@
- \vfromslide@i{\xydashl@}@\czeroEdge@ \leave@ \idfromc@{@m2}%
- \DN@{\cfromid@{@p}\swap@\cfromid@{@c}\no@@}%
- \else \DN@{\enter@\cplusthec@
- \enter@\DirectionfromtheDirection@ \begingroup \belowDirection@ \xydashl@
- \vfromslide@i{#1\xydashl@}@\czeroEdge@ \leave@
- \idfromc@{@m2}\cfromid@{@p}\swap@\cfromid@{@c}%
- \edef\next@{\codeof\dcurveObject@}%
- \ifx\next@\empty\DN@{\connect@\crv{"@m2"}}%
- \else
- \DNii@####1{\connect@\crv{####1}}\expandafter\DN@\expandafter{%
- \expandafter\nextii@\expandafter{\dcurveObject@"@m2"}}%
- \fi \next@ }\fi
-%% \enter@\cfromthec@\sinit@\cfromid@{@m2}\senter@\leave@
-%% \expandafter\connect@\expandafter\crvs\expandafter{\dcurveObject@}%
-%% \sinit@\sleave@
-%% }\fi
- \fi\fi \next@
-%
- \DN@{#1}\ifx\next@\empty\relax\else \ifx #5o\relax\else
- \if\@mod@ @\DN@{\enter@\pfromthep@ \Creset@@
- \ifx #5t\relax
- \PLACEedgec@ \PLACEedgep@ \def\PLACEf@{{.5}}%
- \else \def\next@{\crvreset@}%
- \ifx\next@\Creset@@
- \gettwocelledges@ \edef\PLACEf@{{\expandafter\removePT@\the\dimen@}}%
- \else \PLACEedgec@ \PLACEedgep@ \def\PLACEf@{{.5}}\fi
- \fi
- \expandafter\Calong@@\PLACEf@ \czeroEdge@ \leave@
- \edef\tmp@{\codeof\modmapobject@}\ifx\tmp@\empty\DN@{\drop@{\dir}{|}}%
- \else \DNii@####1####{\drop@{####1}}%
- \DN@{\expandafter\nextii@\modmapobject@{}}\fi
- \next@ }\else\DN@{\relax}\fi
- \next@ \fi\fi
-%
- \DN@{#7}\ifx\next@\empty\DN@{\relax}\else
- \DNii@{{}}\ifx\next@\nextii@\DN@{\relax}\else
- \ifx @#4\relax\DN@{\relax}\else
- \DN@{\enter@\pfromthep@ \Creset@@
- \Calong@@{.5}\czeroEdge@ \leave@
- \enter@\cplusthec@
- \enter@\DirectionfromtheDirection@ \begingroup
- \DN@{#1}\ifx\next@\empty\dimen@\z@ \else\dimen@=#1\p@\fi
- \ifx #5t\relax \ifdim\dimen@<\z@ \belowDirection@ \xydashl@
- \else \aboveDirection@ \xydashl@ \fi
- \else \ifdim\dimen@<\z@ \aboveDirection@ \xydashl@
- \else \belowDirection@ \xydashl@ \fi
- \fi \dimen@=#4\p@ \if\@mod@ @\relax
- \advance\dimen@\ifdim\dimen@<\z@-\fi.5\p@\fi
- \edef\next@{\expandafter\removePT@\the\dimen@}%
- \expandafter\vfromslide@i\expandafter{\next@\xydashl@}@\leave@
- \droptwocelllabel@{#7}}%
- \fi\fi\fi \next@
-%
- \DN@{#1}\ifx\next@\empty\relax\else
- \ifx #5o\relax
- \else\ifx #5b\relax % tip at start only
- \enter@ {\pfromthep@ }\Creset@@ \PLACEedgec@
- \Calong@@{1}\czeroEdge@ \leave@
- \edef\next@{\codeof\twocelltail@}%
- \ifx\next@\empty \DN@{\dir{>}}%
- \ifx\next@\twocellhead@\drop@{\dir}{>}%
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocellhead@{}%
- \fi
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\drop\twocelltail@{}%
- \fi
- \else\ifx #5/\relax
- \enter@{\pfromthep@}\Creset@@ \PLACEedgep@
- \Calong@@{0}\czeroEdge@ \leave@
- \edef\next@{\codeof\twocelltail@}%
- \ifx\next@\empty \DN@{\dir{>}}%
- \ifx\next@\twocellhead@\drop@{\dir}{<}%
- \else
- \reverseDirection@\DNii@##1##{\drop@{##1}}%
- \expandafter\nextii@\twocellhead@{}\reverseDirection@
- \fi
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocelltail@{}%
- \fi
- \else\ifx #5@\relax % no tips at all
- \else % tip at end...
- \enter@\pfromthep@ \Creset@@ \PLACEedgec@
- \Calong@@{1}\czeroEdge@ \leave@
- \edef\next@{\codeof\twocellhead@}%
- \ifx\next@\empty\drop@{\dir}{>}%
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocellhead@{}%
- \fi
- \ifx #5B\relax % ... and also at start.
- \enter@ {\pfromthep@ }\Creset@@ \PLACEedgep@
- \Calong@@{0}\czeroEdge@ \leave@
- \edef\next@{\codeof\twocelltail@}%
- \ifx\next@\empty\DN@{\dir{>}}%
- \ifx\next@\twocellhead@\drop@{\dir}{<}%
- \else
- \reverseDirection@\DNii@##1##{\drop@{##1}}%
- \expandafter\nextii@\twocellhead@{}\reverseDirection@
- \fi
- \else
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocelltail@{}%
- \fi
- \else
- \edef\next@{\codeof\twocelltail@}%
- \ifx\next@\empty\relax\else
- \enter@ {\pfromthep@ }\Creset@@ \PLACEedgep@
- \Calong@@{0}\czeroEdge@ \leave@
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\twocelltail@{}%
- \fi\fi
- \fi\fi\fi
- \fi\fi
-%
-% the Arrow
-%
- \DN@{#1}\ifx\next@\empty\dimen@=\z@\else\dimen@=#1\p@\fi
- \ifdim\dimen@<\z@ \cfromid@{@m2}\swap@\cfromid@{@m1}%
- \else \cfromid@{@m1}\swap@\cfromid@{@m2}%
- \fi \no@@ \cfromid@{@m}%
-%
- \ifx\Arrowtok@\empty
-%
- \else\DN@{_}\edef\next@{\codeof\next@}\ifx\next@\Arrowtok@
- \enter@{\pfromthep@ \cplusthec@}\dimen@=#2\xydashl@
- \enter@\DirectionfromtheDirection@ \begingroup
- \expandafter\vfromslide@i\expandafter{\the\dimen@}@\czeroEdge@
- \leave@ \idfromc@{@m}%
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\Arrowobject@{}%
-% \drop@{\dir}{=>}%
-%
- \else\DN@{^}\edef\next@{\codeof\next@}\ifx\next@\Arrowtok@
- \DN@{_}\edef\Arrowtok@{\codeof\next@}%
- \enter@{\pfromthep@ \cplusthec@}\dimen@=#2\xydashl@
- \enter@\DirectionfromtheDirection@ \begingroup
- \expandafter\vfromslide@i\expandafter{\the\dimen@}@\czeroEdge@
- \leave@ \idfromc@{@m}\reverseDirection@
- \DNii@##1##{\drop@{##1}}\expandafter\nextii@\Arrowobject@{}%
-% \drop@{\dir}{=>}%
-%
- \else \DN@{=}\edef\next@{\codeof\next@}\ifx\next@\Arrowtok@
- \enter@{\pfromthep@ \cplusthec@}%
- \dimen@=#2\xydashl@ \advance\dimen@\xydashl@
- \enter@\DirectionfromtheDirection@ \begingroup
- \expandafter\vfromslide@i\expandafter{\the\dimen@}@\czeroEdge@
- \leave@ \idfromc@{@m2}%
- \cfromid@{@m}%
- \enter@{\pfromthep@ \cplusthec@}%
- \dimen@=#2\xydashl@ \advance\dimen@-\xydashl@
- \enter@\DirectionfromtheDirection@ \begingroup
- \expandafter\vfromslide@i\expandafter{\the\dimen@}@\czeroEdge@
- \leave@ \idfromc@{@m1}%
- \cfromid@{@m2}\swap@\cfromid@{@m1}\connect@{\dir 2}{-}%
- \fi\fi\fi\fi
-%
-% label on the Arrow
-%
- \DN@{#8}\ifx\next@\empty\DN@{}\else\DN@{%
- \ifx\Arrowtok@\empty
- \Calong@@{.5}%
- \else\DN@{=}\edef\next@{\codeof\next@}\ifx\next@\Arrowtok@
- \Calong@@{.5}%
- \else\DN@{_}\edef\next@{\codeof\next@}\ifx\next@\Arrowtok@
- \cfromid@{@m}%
- \fi\fi\fi
- \enter@\cplusthec@
- \enter@\DirectionfromtheDirection@ \begingroup \aboveDirection@\xydashl@
- \ifx\Arrowtok@\empty
- \def\tmp@{0pt}%
- \else\DN@{=}\edef\next@{\codeof\next@}\ifx\next@\Arrowtok@
- \def\tmp@{\xydashl@}%
- \else\DN@{_}\edef\next@{\codeof\next@}\ifx\next@\Arrowtok@
- \def\tmp@{1.2\xydashl@}%
- \else\def\tmp@{0pt}%
- \fi\fi\fi
- \expandafter\vfromslide@i\expandafter{\tmp@}@\czeroEdge@ \leave@
- \droptwocelllabel@{#8}%
- }\fi \next@
- \leave@ }%
-\DOCMODE)
-
-These are used to establish the location for
-the module-map indicator, giving best aesthetic appeal.
-It finds the location whose parameter value is
-the average of half-way along the complete curve and
-the average of parameter values at the the edges.
-
-\DOCMODE(
-\xydef@\gettwocelledges@{%
- \bgroup \the\crvpts@
- \edef\next@{\edges@}%
- \expandafter\gettwocelledges@@\next@ }
-
-\xydef@\gettwocelledges@@#1;#2,#3;#4,{%
- \dimen@=#2\advance\dimen@-#4\relax
- \advance\dimen@ 2\p@ \divide\dimen@ by4 \relax
- \edef\next@{\egroup\dimen@=\the\dimen@ }\next@}%
-\DOCMODE)
-
-\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\paragraph*{The end \& Log}\leavevmode
-
-DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-\DOCMODE(
-\xyendinput
-
-% $Log: xy2cell.doc,v $
-% Revision 3.3 1996/12/18 14:21:23 ross
-% Ross's version
-%
-% Revision 3.3.1.1 1996/12/18 08:49:34 ross
-% *** empty log message ***
-%
-% Revision 3.1 1995/09/05 20:36:33 ross
-% Release!
-%
-% Revision 3.0 1995/07/07 20:13:19 ross
-% Major release w/new User's Guide!
-%
-% Revision 2.14 1995/07/05 22:11:25 kris
-% Buglets...
-%
-% Revision 2.13 1995/07/04 15:04:51 ross
-% Ready for release of v3.
-%
-% Revision 2.12 1994/10/25 03:01:14 ross
-% Final 3beta release [bug fixes & AMS-LaTeX fitting].
-%
-% Revision 2.10 1994/07/01 01:19:46 ross
-% removed undefined references
-%
-% Revision 2.9 1994/06/09 12:51:27 ross
-% Release 3beta.
-%
-% NEW for version 2.9 based on unreleased code for version 2.6+.
-\DOCMODE)
-
-\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-% Tell Emacs that this is a LaTeX document and how it is formatted:
-% Local Variables:
-% mode:latex
-% fill-column:77
-% fill-prefix:""
-% End: